[ntp:hackers] restrict and IPv6 issues

Dave Hart davehart at gmail.com
Tue May 19 05:52:59 UTC 2009


http://bugs.ntp.org/1192 was just filed pointing out that ntpd
4.2.5p177 throws a syntax error given a ntp.conf directive starting
with:

restrict -6 default

I assume that "restrict -6 default" used to work, based on the bug
report.  In glancing at the code, I see another problem that I
consider a bug, but I'm interested in hearing from anyone who
disagrees.  ntpd 4.2.5 maintains two restriction lists, one for IPv4,
and one for IPv6.  Currently, "restrict default ..." applies to only
one protocol or the other, IPv4 by default, IPv6 if ntpd was invoked
with the -6 switch.  It seems to me "restrict default" should apply to
both protocols.  Once bug 1192 is fixed and "restrict -4 default" and
"restrict -6 default" are again supported, they should of course apply
to only the given protocol.

As an aside, my experience with ntpd on IPv6 is extremely limited,
frustratingly, as over two years after Martin got ntpd IPv6 support
working on Windows, that code is still in limbo.  I don't run any
Unix-based machines to test ntpd IPv6 support on myself, though a kind
NTP user has given me a shell on their Linux box and set me up with
sudo to be able to run ntpd, however they do not use IPv6.  I'm
comfortable mucking around in ntp_scanner.c and ntp_parser.y and
intend to fix 1192 and the bug I identified, but it sure as heck isn't
to scratch a current itch.  Hopefully it won't be too many more years
before I can test ntpd IPv6 stuff on my Windows machines.

Cheers,
Dave Hart


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